Edge guidance and hemming devices

ABSTRACT

Automatic edge guidance and hemming of flexible sheet material, especially fabric, is achieved by one or more jets of fluid, commonly air, directed normal to the margin of the material and into a duct formed for guiding and folding the margin. A roll hem may be produced in a single jet-and-duct device, or single and double hem folds may be provided employing a plurality of preferably laterally aligned and spaced feed-duct sections.

United States Patent Inventor Richard W. Gray Marblehead, Mass.

Appl. No. 6,510

Filed Jan. 28, 1970 Patented July 27, I971 Assignee USM Corporation Boston, Mass.

EDGE GUIDANCE AND HEMMING DEVICES References Cited UNITED STATES PATENTS 2,630,772 3/1953 Ederer Ill/DIG. 2 3,204,591 9/1965 Pickett 112/136 X 3,252,437 5/1966 Pickelt 112/136 Primary Examiner-H. Hampton Hunter Attorneys-Richard A Wise, Richard B. Megley and Carl E.

Johnson ABSTRACT: Automatic edge guidance and hemming of flexi ble sheet material, especially fabric, is achieved by one or more jets of fluid, commonly air, directed normal to the margin ofthe material and into a duct formed for guiding and folding the margin. A roll hem may be produced in a single jetand-duct device, or single and ,double hem folds may be provided employing a plurality of preferably laterally aligned and spaced feed-duct sections.

. SHEET 1 OF 2 PATENTEU JUL27 m:

EDGE GUIDANCE AND HEMMING DEVICES CROSS-REFERENCE TO RELATED APPLICATION Application, Ser. No. 9l85 filed Feb. 6, I970, in the name of Paul Morgan pertains to a sheet orienting mechanism comprising an edge gage, a channel loosely confining a sheet to be operated on, and an airflow device for streaming air parallel with a sheet in the channel to cause the sheet to maintain progressive edge contact with the edge gage.

BACKGROUND OF THE INVENTION This invention relates to a device for hemming sheet material automatically and uniformly. The invention is herein described and illustrated as embodied in a hemming accessory for use in a sewing machine or in a machine for adhesively securing a margin folded upon itself, but it will be understood that the invention is not necessarily limited to operation upon flexible sheet material of any particular type nor to operation in conjunction with any specific means for securing or otherwise treating the workpiece margin as it exits from the hemmer.

Numerous mechanisms have hitherto been provided for enabling an operator to hem a border. Despite the great variety of mechanisms available for hemming, so far as known they all, or nearly all, rely on the operator's skill and close attention to obtain uniformly good production. Customarily she must manually continuously control positioning movement of the flexible margin both in a direction against a member abutting the workpiece edge and at the same time smooth and restrain the work locally as it is moved by feed mechanism in another direction toward an instrumentality, eg, a stitchforming means, for operating on the folded margin. Such manipulation is burdensome and tedious. Efforts to ease wear and tear" on the operator have encountered difficulties because, for instance, fabric pieces to be hemmed are often flimsy, tend to snag, have different degrees of sliding friction, and are ofmany shapes and sizes.

One approach to automating fabric handling is disclosed in a copending application, Ser. No. 647,784, filed June 21, I967 in the name of Richard R. Walton now U.S. Pat. No. 3,531,103. It contributes a significant advance in the art because it enables successive edge aligned pieces of a stack to be singly positioned with accuracy at a desired delivery point for further processing. The next station in an automatic garment manufacturing system may, for example, automatically hem the fabric pieces as they are thus presented to the hemming device disclosed in the present application.

The prior art includes US. Pat, No. 3,204,591, for example, in which a work-guiding device having an edge guiding surface extending in the direction of work travel also has an air conduit for delivery of air under pressure obliquely against a work-supporting surface spaced from the edge guiding surface and laterally of the direction of travel of the work for urging its edge against the guiding surface. Such an arrangement is distinguished from embodiments of the present invention wherein fluid flow is directed normal to and beyond the supporting surface to deflect the margin of the workpiece and thus laterally feed and turn the margin progressively. The entraining of air in the hemming duct by a high-speed jet causes an air bearing effect and imparts sufficient force to ensure that the work edge will advance laterally until it abuts the stop sur-. face ofthe conduit.

SUMMARY OF THE INVENTION In view of the foregoing it is a main object of this invention to provide, in combination with a machine including an operating tool and means for feeding sheet material to and through the zone of the tool, a guiding and hemming device wherein a flexible sheet may be initially presented laterally even if with some inexactness and the device will then automatically position the sheet with respect to the direction of feed of the feeding means and form a uniform hem to be progressed through the work station.

Another and more specific object of this invention is to provide a simple, reliable, stationary hemming accessory for a margin securing machine, such as a stitcher, the accessory being mounted ahead of an operating instrumentality of the machine and adapted to induce lateral in-feeding of sheet material for predetermined fluid forming of its margin, the spent fluid aiding in feeding of the material to the operating instrumentality.

Still another object of the present invention is to provide, in combination with a fabric feeding machine employing airflow, a pneumatic edge folding device capable of efficient use of its air supply for forming a hem on successive pieces as received from the feeding machine.

To these ends, and in accordance with a feature of the invention, there is provided in combination with a machine having an operating tool and means for feeding sheet material toward the operating locality of the tool, an improved edge guide and hemming device disposed immediately ahead of the tool and comprising at least one duct turned back upon itself and formed to receive and enfold a portion of the margin of the material and a fluid-directing nozzle adjacent to a turn in the duct and operative progressively to deflect overhanging or unsupported marginal portions of the material to urge them laterally edgewise into the duct.

As herein shown a series of duct-and-nozzle units may be employed in lateral spaced relation, the hem to be formed being defined at its outer border by the aligned internal U shaped surfaces of the respective ducts and further defined at its inner border by aligned closed ends of the ducts. The fluid medium ordinarily preferred is air fed through the nozzle under pressure. The arrangement of each duct and its nozzle is such that the air jet is directed toward and mainly emitted into a bend in the duct passage thereby causing the margin of the sheet to advance edgewise therein while progressively conforming to the internal contour of the duct.

To ensure that a uniform width of hem exits from that end of the hemming accessory closest to the operating tool, for instance a reciprocable needle in a conventional sewing machine, there is provided as a further feature ofthe invention a stationary rod arranged to rest on the worktable of the machine and progressively deflect the under ply of the hem. This rod being affixed to the endmost duct and disposed, for instance, between a presser foot of the sewing machine and the hemming accessory is of a thickness to enable the lower ply of the hem to remain constantly of the same width as to its upper ply.

The foregoing and other features of the invention together with other novel details and combinations of parts will now be more particularly described with reference to preferred embodiments and in connection with the accompanying drawings thereof, in which:

FIG. I is a plan view of an illustrative sectional hemming device adapted for mounting as an accessory on a sewing machine bed, the hem ofa workpiece being shown in relation to a needle and presser foot.

FIG. 2 is a perspective view ofa single section of the device shown in FIG. 1 as modified to provide a single-folded hem on a marginally precemented sheet;

FIG. 3 is a sectional view looking laterally at the presser foot in FIG. I, the hemming device being at a lower level than the machine bed such that the middle ply of a double hem proceeds parallel to the bed;

FIG. 4 is a view corresponding to FIG. 3 but showing the hemmer supported on a level with the machine bed and having a finger for deflecting the lower ply;

FIG. 5 is a view in elevation of an exit end section of the device shown in FIG. 1 and showing the finger of FIG. 4',

FIG. 6 is an enlarged detail, partly in section, of the hemming unit shown in FIG. 5, a hemming margin being received;

FIG. 7 is a perspective of a hemming duct and nozzle unit similar to that shown in FIG. 6, but wherein a top work constraining plate is advantageously omitted and a restricted inlet orifice is not enclosed by the duct;

FIG. 8 is a different perspective of a four-section hemmer; and

FIG. 9 is an enlarged view ofthe duct and nozzle hemmer of FIG. 6 showing a hem formed with the aid ofa second nozzle and in relation to the needle which is to secure the hem.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a straight line multisectioned downturn hemmer generally designated 10 affixed as by screws 12 to a bed 14 ofa sewing machine of conventional type and comprising a reciprocable needle 16 and a cooperating presser foot 18. The hemmer 10 includes a flat base plate 20 on which is secured in parallel relation a series of spaced ducts 22 (FIGS. 5, 6, 9) for laterally receiving and enfolding the margin of sheet material M to be hemmed. As indicated in FIGS. and 9 a duct 22 has a work-supporting strip or surface 24 extending on and laterally beyond the plate 20 and bent back or U- shaped at its margin, and a spaced parallel plate 26. One end 28 of the plate 26 nearest to the needle 16 diverges upwardly to provide a work confining entrance mouth for receiving the initially laterally received material M. An inner portion of the plate 26 may be secured to an underside of the plate 20. The intermediate U-shaped portions 30 of each plate 26 are aligned with corresponding portions of other ducts 22, if employed, to define the external border of the margin and the direction oftravel of the material to be hemmed.

Each duct portion 30 is formed at its bend with a slot or hole 32 (FIG. 6) for receiving the delivery end of a jet nozzle 34 connected to a source of air under pressure, for instance an accumulator 36 (FIGSv 1, 5, 8). Accordingly a stream of air is directed from the nozzle 34 normal to the plane of the worksupporting surface 24 and against the entering unsupported marginal portion of the material as shown in FIG. 6 causing the material progressively to be deflected and conformed to the bend or bends of the ducts 22 as indicated in FIG. 9. This view also illustrates usage of a supplemental or second air deflector nozzle 34. Air entrained in the ducts acts to urge the material M laterally until it abuts an end stop provided in the duct as, for instance, an inturned extremity 38 (FIGS. 5 and 6) of the plate 26. Spent air escapes from the open ended ducts on opposite surfaces of the hem material, the airflow between the strips 24 and under the material being effective to serve as an air bearing for aiding feeding of the material toward the needle 16.

It will be understood that a hemmer l0 employing only a single duct-nozzle unit of the type described is at times satisfactory for quite limp fabric pieces and those which may have curved margins. It will also be appreciated that the single or multisectioned hemming units may extend at an angle to the bed 14 ofa machine on which they are mounted or may lie on a path which arcuately merges with the machine bed. As indicated in FIGS. 1 and 5, the accumulator 36 is supported by a bracket 40 secured between the plate 26 and the nozzle 34, and the accumulator has supportive connection to an air supply pipe.

In FIGS. 2 and 7 a simpler form of duct, one generally designated 42 that is uncovered, i.e. omits the plate 26, is illustrated. The duct 42 is often preferred for the reason that automatic pickoff elements (not shown) of a machine for successively transferring fabric pieces to the hemming device can then control the leading edge of each piece and ad vantageously release it more immediately adjacent to the margin forming nozzle or nozzles 34. As shown in FIGS. 2 and 7 the duct comprises a work-supporting U-shaped strip 24 and an upwardly extending edge guiding plate 44 the lower portion of which provides a terminal abutment for the margin of the material M and is bent in spaced parallel relation to the strip 24. An upper portion 46 of the plate 44 desirably extends normal to the supporting surface of the strip 24 and is offset therefrom to define an inlet 48 for the laterally fed sheet material M. The nozzle 34, which may have a tapered inlet end as shown in FIG. 7 for concentrating air impingement may be supported on the plate portion 46 to direct a fluid jet into the inlet 48 and thereby progressively deflect the margin of the material M until the hem conforms to the internal shape of the duct 42.

In FIG. 2 the duct 42 may be adapted for hemming precemented margins 50, the plates 24, 44 being heated to activate the cement, and the air emitted from the nozzle 34 also preferably being heated for this purpose. Then, in lieu of requiring a needle and thread as the securing means for hemming, or in addition thereto, a heated presser foot 18 operating in conventional manner may simultaneously feed the folded margin longitudinally. and, in each feeding step press the activated surfaces 50 together to effect a bonded margin.

The sheet material M to be hemmed is manually or automatically laterally fed edgewise on the strip or strips 24 toward the margin forming air jets emitted from the nozzles 34, an edge of the material being simultaneously introduced into the operating zone of the presser foot 18 or other feeding means. The U-bends of the ducts 42 or 22 are disposed to form a down-turned hem the outer edge of which is parallel to and uniformly spaced from the line of feed effected by the presser foot 18 or other suitable feed means. If the hemming device 10 can be slightly depressed relative to the bed 14 as shown in FIG. 3, the plies of sheet material merge into contiguous relation without distorting or changing the width of the margin as it exits from the duct adjacent to the presser foot 18. When, on the other hand, it is not convenient to mount the hemming accessory slightly lower than the bed 14 as illustrated in FIG. 4, a finger 52 for deflecting the lower ply upwardly is preferably used thereby equalizing the feeding paths of the plies. This finger may be bracketed at its upper end to the accumulator 36 and its lower or ply deflecting end extendsjust ahead of the presser foot to ensure that the marginal portions remain uniform widthwise as they come out ofthe hemmer l0 and are fed by the presser foot 18.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent ofthe United States is:

1. In a machine for securing the margin of sheet material in folded relation and including margin securing means and mechanism for feeding the material to and through the operat ing zone of the securing means, a hemming device ahead of the feeding mechanism and comprising at least one duct arranged laterally edgewise and provided with an inturned passageway for enfolding the material parallel with the feeding direction of the feeding mechanism, and a nozzle disposed to emit a jet of fluid directly into a turn of the passageway for deflecting the material while inducing it to conform mar ginally to the contour ofthe passageway.

2. The machine ofclaim 1 wherein the device includes a se ries of aligned ducts each having a work-supporting surface and a passageway provided with an internal edge guiding surface for enfolding the material along the direction of feed, and a nozzle normal to each of said work-supporting surfaces for directing air into the passageway adjacent to the edge guiding surface.

3. A hemming accessory for mounting on the bed of a margin securing machine and ahead of its sheet feeding means comprising at least one U-bent duct having a work-supporting surface leading into the duct bend, and an associated nozzle beyond said surface for directing margin forming fluid into the duct at its bend, the nozzle being substantially normal to said surface.

4. An accessory as set forth in claim 3 wherein the duct comprises a flat work supporting strip terminating at one side ofthe inlet of the duct, and the other side of the inlet is formed by a second strip extending normal to the work-supporting strip, the nozzle being mounted on the second strip.

5. An accessory as set forth in claim 3 having, intermediate the exit end of the duct and said feeding means, a stationary finger disposed to deflect transversely from the level of said bed a portion of the formed margin of the sheet relative to the remainder of the formed margin whereby widthwise uniformity of the plies of the margin is maintained.

6. In a sewing machine having a bed, stitch-forming mechanism, and a presser foot operable to feed sheet material along a path over the bed and extending to and through the operating zone of said mechanism, a hemming accessory comprising at least one duct-jet device adapted to be mounted on said bed ahead of the presser foot, the duct portion of the device being parallel portions of a pair of flat strips respectively having at least one U-bend, an extension of one of said strips providing a work-supporting surface on which the sheet material to be hemmed may be laterally fed into the duct portion edgewise, the second of said strips extending upwardly from the work-supporting surface and laterally spaced therefrom toprovide an inlet for the duct portion and an edge gage aligned with said path of feed, and the device including a nozzle arranged to direct a jet of fluid directly into the inlet just ahead of said second strip to advance the material laterally into the duct portion and past said edge gage.

7. The sewing machine of claim 6 wherein the device further includes a second nozzle arranged to direct a fluid jet into the duct adjacent another bend thereof to advance the material laterally. 

1. In a machine for securing the margin of sheet material in folded relation and including margin securing means and mechanism for feeding the material to and through the operating zone of the securing means, a hemming device ahead of the feeding mechanism and comprising at least one duct arranged laterally edgewise and provided with an inturned passageway for enfolding the material parallel with the feeding direction of the feeding mechanism, and a nozzle disposed to emit a jet of fluid directly into a turn of the passageway for deflecting the material while inducing it to conform marginally to the contour of the passageway.
 2. The machine of claim 1 wherein the device includes a series of aligned ducts each having a work-supporting surface and a passageway provided with an internal edge guiding surface for enfolding the material along the direction of feed, and a nozzle normal to each of said work-supporting surfaces for directing air into the passageway adjacent to the edge guiding surface.
 3. A hemming accessory for mounting on the bed of a margin securing machine and ahead of its sheet feeding means comprising at least one U-bent duct having a work-supporting surface leading into the duct bend, and an associated nozzle beyond said surface for directing margin forming fluid into the duct at its bend, the nozzle being substantially normal to said surface.
 4. An accessory as set forth in claim 3 wherein the duct comprises a flat work supporting strip terminating at one side of the inlet of the duct, and the other side of the inlet is formed by a second strip extending normal to the work-supporting strip, the nozzle being mounted on the second strip.
 5. An accessory as set forth in claim 3 having, intermediate the exit end of the duct and said feeding means, a stationary finger disposed to deflect transversely from the level of said bed a portion of the formed margin of the sheet relative to the remainder of the formed margin whereby widthwise uniformity of the plies of the margin is maintained.
 6. In a sewing machine having a bed, stitch-forming mechanism, and a presser foot operable to feed sheet material along a path over the bed and extending to and through the operating zone of said mechanism, a hemming accessory comprising at least one duct-jet device adapted to be mounted on said bed ahead of the presser foot, the duct portion of the device being parallel portions of a pair of flat strips respectively having at least one U-bend, an extension of one of said strips providing a work-supporting surface on which the sheet material to be hemmed may be laterally fed into the duct portion edgewise, the second of said strips extending upwardly from the work-supporting surface and laterally spaced therefrom to provide an inlet for the duct portion and an edge gage aligned with said path of feed, and the device including a nozzle arranged to direct a jet of fluid directly into the inlet just ahead of said second strip to advance the material laterally into the duct portion and past said edge gage.
 7. The sewing machine of claim 6 wherein the device further includes a second nozzle arranged to direct a fluid jet into the duct adjacent another bend thereof to advance the material laterally. 